You can use either a Web server plug-in, or a WebSphere
Application Server proxy server to provide session affinity, failover
support, and workload balancing for your WebSphere Application Server
topology .
After you install the product, you can set up either a Web server
plug-in, or a WebSphere Application Server proxy server to establish
communication between an application and a remote client.
- A WebSphere Application Server Web server plug-in provides an
interface between a Web server and an application server. The Web
server plug-in determines the server to which a client request for
dynamic content, such as servlets, needs to be routed.
- A WebSphere Application Server proxy server is a
specific type of application server that routes HTTP requests to content
servers that perform the work. The WebSphere Application Server proxy
server can be the initial point of entry for requests to servers in
your enterprise environment. However, because a WebSphere Application
Server proxy server is not safe for DMZ deployment, a WebSphere Application
Server proxy server is typically fronted by a web server, or used
in internal only environments where stringent host security requirements
are not required.
You can also use the on demand router (ODR), that is provided with
the WebSphere eXtended Deployment product, as a reverse proxy between
an HTTP client and a clustered application, or a partitioned application.
See the WebSphere eXtended Deployment Information Center at http://publib.boulder.ibm.com/infocenter/wxsinfo/v7r0/index.jsp
for more information about using ODR.
The traditional topology, using your Web server of choice and the
corresponding Web server plug-in, is recommended unless:
- You want to use specific features of the ODR or a WebSphere Application
Server proxy server.
- You want to use another function, such as Session Initiation Protocol
(SIP) or WS-Addressing affinity/failover, which requires a WebSphere
Application Server proxy server.
The following tables compare the core application server frontend
functionality, and the non-core functionality of a Web server plug-in
running in a modern Web server, such as the IBM HTTP Server, based
on Apache HTTP Server, and a WebSphere Application Server proxy server.
Table 1. Core functionality. This table compares
the functionality that a Web server plug-in, and a WebSphere Application
Server proxy server provide.
Functionality |
Web server plug-in |
WebSphere Application Server proxy
server |
Session affinity |
Yes |
Yes1, 2 |
DMZ ready |
Yes |
No |
Custom advisors are supported |
No |
No3 |
Service Level Agreement (SLA) |
No |
No |
QoS/Throttling |
No |
No |
SIP proxy |
No |
Yes |
ESI dynamic Caching |
Yes |
Yes4 |
Managed from the administrative console |
Yes |
Yes |
Stream caching (large response caching) |
Yes |
No5 |
Dynamically receive management events6 |
No |
Yes |
Multi cells routing |
No |
Yes6 |
Performance monitoring |
Yes7 |
Yes7 |
Load Balancing (weighted round-robin) |
Yes8 |
Yes9 |
Routing rules are configurable |
No10 |
Yes |
Interoperability with WLM |
Yes11 |
Yes |
Web service affinity and failover |
No |
Yes12 |
Generic server cluster (GSC) affinity and failover |
No |
Yes13 |
Table notes:
- Session affinity is supported for WebSphere Application Server
managed resources. However, some session management custom properties,
such as HttpSessionCloneId, are not supported.
- For generic server routing, where the resources are not WebSphere
Application Server managed resources, active session affinity and
passive session affinity need to be configured under generic server
routing action.
- Custom advisors are supported in Version 7.0.
- WebSphere Application Server proxy servers do not support fragment
caching. Only whole page caching, and the ESI invalidation servlet
are supported.
- Stream caching is provided in Version 7.0
- Requires core group bridge setup between the proxy cell and other
cells.
- The Web server plug-in statistics are obtained from request metrics.
- WebSphere Application Server proxy server statistics can be retrieved
from Tivoli performance viewer, ARM, and performance mBeans.
- Random Load balancing is supported in addition to weighted round
robin.
- Web server plug-in can only do static routing.
- A Web server plug-in indirectly has interoperability with WLM
through the exchange of dynamic workload manager (DWLM) Partition
Tables between the Web server plug-in and WebSphere Application Server.
The plug-in uses these tables for dynamic routing and failover scenarios
within a cluster.
- The DataPower appliance manager provides faster
Web service affinity and failover service than Java proxy provides.
- Proxy server supports load balancing and failover
for generic server clusters with passive and/or active affinity.
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Table 2. Functionality provided outside of the Web server plug-in. This table provides a comparison of the functionality that a
typical Web server, that is hosting a Web server plug-in, and a WebSphere
Application Server proxy server provide outside of the core application
server frontend functionality. See your Web server documentation for
a complete description of the functionality that your particular Web
server provides.
Functionality |
Web server plug-in used with either
the IBM HTTP Server or the Apache Web Server |
WebSphere Application Server proxy
server |
Common Gateway Interface (CGI) |
Yes |
No |
Request URI rewriting |
Yes |
No |
Efficient static file serving |
Yes |
No1 |
Compression |
Yes |
Yes |
Response filtering |
Yes |
No2 |
SSL termination |
Yes |
Yes |
Cryptographic Accelerator3 |
Yes |
Yes4 |
FIPS |
Yes |
Yes |
Third-party/customer-written plug-ins |
Yes |
No |
Logging |
Yes |
Yes5 |
Custom Logging |
Yes |
No |
Disk caching |
Yes |
Yes |
Asynchronous request handling |
none or partial6 |
Yes7 |
Table notes:
- WebSphere Application Server proxy servers support basic static
file serving in Version 7.0
- WebSphere Application Server proxy servers support HTML link rewriting
in Version 7.0.
- This functionality only applies to Cryptographic Accelerators
that WebSphere Application Server supports. See the Supported hardware and software Web page .
- The support is provided by IBM JDK/JCE.
- Only NCSA common format is supported.
- The connection between a Web server plug-in and an application
server is synchronous and consumes a thread while reading/writing
or waiting for data. See your Web server documentation for information
about how your particular Web server handles client connections.
- Proxy server is optimized to handle AJAX long polling
requests under large scale deployments.
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